Method and apparatus for handling outstanding interconnect transactions

Abstract

A method and apparatus for handling outstanding interconnect transactions between a master device and an interconnect component. For example, a transaction intervention module coupled to an interconnect component and a master device of the interconnect component. The transaction intervention module is arranged to receive an indication of a functional state of the master device. If the master device is indicated as being in a faulty functional state the transaction intervention module is further arranged to determine whether any interconnect transactions initiated by the master device with the interconnect component are outstanding. If it is determined that at least one interconnect transaction initiated by the master device is outstanding, the transaction intervention module is arranged to finalize the at least one outstanding interconnect transaction with the interconnect component.

The invention claimed is: 
     
       1. A processing system comprising:
 a transaction intervention module coupled to at least one interconnect component and at least one master device of the at least one interconnect component; 
 the transaction intervention module is arranged to receive an indication of a functional state of the at least one master device, and if the at least one master device is indicated as being in a faulty functional state the transaction intervention module is further arranged to:
 determine whether any interconnect transactions initiated by the at least one master device with the at least one interconnect component are outstanding; and 
 if it is determined that at least one interconnect transaction initiated by the at least one master device is outstanding, finalise the at least one outstanding interconnect transaction with the at least one interconnect component. 
 
 
     
     
       2. The processing system of  claim 1 , wherein upon determining that at least one interconnect transaction initiated by the at least one master device is outstanding, the transaction intervention module is arranged to:
 determine whether the at least one outstanding interconnect transaction comprises a write transaction; and 
 if it is determined that the at least one outstanding interconnect transaction comprises a write transaction, provide data to the at least one interconnect component to finalise the outstanding write transaction. 
 
     
     
       3. The processing system of  claim 2 , wherein if it is determined that the at least one outstanding interconnect transaction comprises a write transaction, the transaction intervention module is arranged to provide data to the at least one interconnect component comprising at least one of:
 a predefined default data pattern; 
 buffered transaction data. 
 
     
     
       4. The processing system of  claim 1 , wherein upon determining that at least one interconnect transaction initiated by the at least one master device is outstanding, the transaction intervention module is arranged to:
 determine whether the at least one outstanding interconnect transaction comprises a read transaction; 
 if it is determined that the at least one outstanding interconnect transaction comprises at least one read transaction, detect returning read transactions for the at least one master device; and 
 upon detecting a returning read transaction for the master device, finalise the detected returning read transaction. 
 
     
     
       5. The processing system of  claim 4 , wherein the transaction intervention module is arranged to store the returning data for the at least one outstanding read transaction within at least one memory element. 
     
     
       6. The processing system of  claim 1 , wherein the transaction intervention module is arranged to:
 monitor an interface between the at least one master device and the at least one interconnect component; 
 maintain at least one transaction counter for outstanding interconnect transactions initiated by the at least one master device; and 
 determine whether any interconnect transactions initiated by the at least one master device with the at least one interconnect component are outstanding based on the at least one transaction counter. 
 
     
     
       7. The processing system of  claim 6 , wherein the transaction intervention module is arranged to:
 detect transaction activity between the at least one master device and the at least one interconnect component; 
 increment the at least one transaction counter, if the detected transaction activity relates to the at least one master device initiating a transaction; and 
 decrementing the at least one transaction counter, if the detected transaction activity relates to the at least one master device finalising a transaction. 
 
     
     
       8. The processing system of  claim 7 , wherein the transaction intervention module is arranged to maintain a read transaction counter and a write transaction counter. 
     
     
       9. The processing system  claim 1 , wherein the transaction intervention module is arranged to generate a fault recovery signal when all outstanding transactions initiated by the at least one master device have been finalised. 
     
     
       10. The processing system of  claim 1 , wherein if the at least one master device is indicated as being in a faulty functional state the transaction intervention module is further arranged to initiate a timer and generate a fault recovery signal upon the first to occur of:
 expiry of the timer; and 
 all outstanding transactions initiated by the at least one master device being finalised. 
 
     
     
       11. A method of handling outstanding interconnect transactions using a transaction intervention module coupled between an interconnect component of a processing device and a master device of the interconnect component; the method comprising receiving an indication of a functional state of the master device, and if the at least one master device is indicated as being in a faulty functional state the method of handling outstanding interconnect transactions using the transaction intervention module further comprising:
 determining whether any interconnect transactions initiated by the master device with the interconnect component are outstanding; and 
 if it is determined that the at least one interconnect transaction initiated by the master device is outstanding, finalising the at least one outstanding interconnect transaction with the at least one interconnect component. 
 
     
     
       12. The method of  claim 11 , wherein upon determining that at least one interconnect transaction initiated by the master device is outstanding, the method of handling outstanding interconnect transactions using the transaction intervention module further comprises:
 determining whether the at least one outstanding interconnect transaction comprises a write transaction; and 
 if it is determined that the at least one outstanding interconnect transaction comprises a write transaction, providing data to the at least one interconnect component to finalise the outstanding write transaction. 
 
     
     
       13. The method of  claim 11 , wherein upon determining that at least one interconnect transaction initiated by the master device is outstanding, the method of handling outstanding interconnect transactions using the transaction intervention module further comprises:
 determining whether the at least one outstanding interconnect transaction comprises a read transaction; 
 if it is determined that the at least one outstanding interconnect transaction comprises at least one read transaction, detecting returning read transactions for the master device; and 
 upon detecting a returning read transaction for the master device, finalising the detected returning read transaction. 
 
     
     
       14. The method of  claim 11 , wherein the method of handling outstanding interconnect transactions using the transaction intervention module comprises:
 monitoring an interface between the master device and the interconnect component; 
 maintaining at least one transaction counter for outstanding interconnect transactions initiated by the master device; and 
 determining whether any interconnect transactions initiated by the master device with the interconnect component are outstanding based on the at least one transaction counter. 
 
     
     
       15. A transaction intervention device, comprising:
 a connection interface coupled to an interconnect component and to a master device of the interconnect component; 
 a transaction buffer configured to store data associated with transactions between the interconnect component and the master device; 
 a transaction handler configured 1) to receive an indication of a functional state of the master device, 2) to determine if a transaction initiated by the master device is outstanding when the indication indicates that the master device is in a fault condition, and 3) to finalize the outstanding transaction when the transaction handler determines that the transaction is outstanding without resetting the master device. 
 
     
     
       16. The transaction intervention device of  claim 15 , further comprising:
 a read counter configured to maintain a count of outstanding read transactions from the interconnect component to the master device, wherein in determining if the transaction initiated by the master device is outstanding, the transaction handler is further configured to determine that the read counter includes a non-zero number of outstanding read transactions. 
 
     
     
       17. The transaction intervention device of  claim 16 , wherein in finalizing the outstanding transaction the transaction handler is further configured to store data from the interconnect component to the transaction buffer. 
     
     
       18. The transaction intervention device of  claim 15 , further comprising:
 a write counter configured to maintain a count of outstanding write transactions from the master device to the interconnect component, wherein in determining if the transaction initiated by the master device is outstanding, the transaction handler is further configured to determine that the write counter includes a non-zero number of outstanding write transactions. 
 
     
     
       19. The transaction intervention device of  claim 18 , wherein in finalizing the outstanding transaction, the transaction handler is further configured to send data from the transaction buffer to the interconnect component. 
     
     
       20. The transaction intervention device of  claim 15 , wherein in finalizing the outstanding transaction the transaction handler is further configured to determine that the outstanding transaction is a write transaction from the master device to the interconnect component, and to send a predefined default data pattern to the interconnect component when the outstanding transaction is a write transaction.